December 4, 1996

Adelie penguin inspects microphone cable

I had returned to McMurdo on the previous evening after the trip to Cape Royds and found that Buck Tilley would be able to work with me out at the sea ice edge. We were hoping to record killer whales, minke whales and perhaps leopard seals. It was certainly a hit or miss proposition, as one never knows what is out along the edge on any given day. At McMurdo, the day looked promising--it was in the mid-20s with an onshore breeze blowing. The windchill put a bite in the air, but a trip to the ice edge was definitely on.

By chance, I had breakfast with Samantha Tisdel, a fire house dispatcher, who had the day off. Since her ony plans included doing laundry, I invited her to join us for the outing. Samantha is a writer and journalist from Ouray, Colorado. She is bright and inquisitive and has a nice way of framing her experiences in words. I got to know her when she was writing about my sound recording work for the Antarctic Times--the McMurdo weekly. An adventuresome spirit, Samantha taught English in Tsing Tao province in China for a year and has traveled extensively throughout rural China and Southeast Asia. A travel piece, in which she describes one of her culinary experiences eating fried grasshoppers, will be appearing soon in the Seattle Times.

After the usual morning of packing and repacking gear, getting food from A.C. Hitch at the Berg Field Center, a Jiffy Ice Auger from the mechanical Equipment Center, we were ready to go at about 9:30am. Samantha and I picked up Buck at the Field Training Center and dropped our equipment and survival bags at the ice transition, where the snowmobiles were parked. It had been warming up and the snow was beginning to get heavy and slushy; big caterpillar rigs plowed and resurfaced the area, which sees a lot of traffic out to he ice runway. We decided that we would take two ski-doos, one with a sled to haul everything out.

Clouds of all strata stretched across the sound--cirrus wisps touched a deep blue and a muddy yellow cumulus front rose before us. Mt. Erebus steamed from its vent and a broken patch of sun caused the crevasse field to glow on the slopes below. We made for the Penguin Ranch, where Gerry and Carsten Kooyman were worked; the rest of their research group had left earlier in the week for the States. Upon arriving, I hardly recognized the place--recent storms had drifted snow around the huts and the penguin corral and the tents had all been pulled up. The snow was so heavy that it depressed the surrounding ice. "The dive hole in the hut overflowed and we had to have someone come out and clear the area out. It cost us a few days of work," explained Gerry. We touched base about the condition of the sea ice beyond the ranch and Gerry looked up some Global Positioning System (GPS) longitude and latitude numbers and told us about some dangerously thin and slushy stretches about 5 kilometres in the direction of Cape Royds.

Buck decided to aim for the sea ice edge in another direction, near where the Nathanial B. Palmer, or Natty B., research ship had been several weeks before. We thanked Gerry and proceeded with caution across the ice; buck stopped periodically to get GPS readings. About 5 kilometres out, in flat light, the horizon and the ice seemed to merge. It was reasonably overcast and the wind had died down to nothing more than an occasional gust of a few knots. Quite suddenly, Buck stopped and stood up on his snowmobile waving to us. Samantha and I had been following at a safe distance of about 100 metres. We slowed down and waited. Buck motioned us to approach; the ice edge was only about 150 metres in front of us! In the filtered, yellowish light, we simply did not see it. The water was like glass and our only real clue was a broken line of Adelie penguins and a lone emperor penguin--who immediately wandered over to take a look at us.

Buck got out his ice auger and a throw rope and we walked, about 50 feet apart, towards the edge--drilling every 60 feet to check ice thickness. The shelf had gone from 7 feet to 3 feet rather quickly, and it remained so right up to the edge. After scouting out the site, Buck determined that we could approach to within 20 feet of the actual edge. With Samantha's help, I assembled my hydrophones and gear. We bored two 4 inch holes into the ice--set apart at a distance of about 200 feet, parallel to the water and ice boundary, and put the hydrophones in. I was curious to listen, as life at the edge and life under the fast ice were different. Weddell seals roam about in the fast ice with relative ease and their wonderous sounds I had been recording over the last few weeks. However, in more open waters leopard seals and killer whales patrol the edge looking for prey.

With the hydrophones lowered to a depth of about 50 feet, I tuned in to distant Weddell seals and a low frequency call that I had not heard before: a modulated, pulsed and pitched sound, like a muted steam whistle with rounded, blooming chugs. I had not heard a killer whale make this sound and guessed at the possibility that it may be a Minke whale. Beneath the telltale whistles, trills and chirps of far off Weddells, this sound occupied a lower frequency niche. Knowing that I would have the opportunity for repeated listening and scrutiny, I let Samantha listen through headphones, while Buck videotaped. The look of delighted surprise on her face was wonderful. "She is gone," observed Buck an hour later, when Samantha had eased back on the ice and was grinning and humming along with her eyes closed. But what was the sound, the new sound we were hearing? I later found out from Gerry Kooyman that it was a leopard seal calling. He mentioned to me that he had heard them calling, through the ice, from a distance of nearly 5 kilometres, when he was out at Cape Washington!

As Samantha listened and got lost in a world of sound, Buck and I talked in whispers about the Adelie penguins, who swam by in groups, porpoising in leaps out of the water. One curious individual ambled over to check us out and was fascinated by the cables that ran from the tape recorder to the hydrophones (see below). The bird paused, stooped and inched in with reserve--they are a little more shy than emperors. Its wings were flushed pink in the inside, having just come from swimming in the water. He lingered for a moment, looking us up and down. A flourish of calling from the edge signaled the passing of another group and the Adelie waddled off to join his flock. Through the headphones a resounding, booming crack was heard. Samantha levitated from her comfortable position; Buck and I reeled around. It was the cracking of ice--a large fissure, no doubt. We looked at the throw rope, which Buck had tied to the snowmobile in such a way so as to indicate if we were drifting. He also did a quick spot check of the GPS. No movement... The last thing we wanted was to go off on a broken floe, into the pack ice, never to be seen again--it would have ruined the whole day!

The wind started to pick up and we could discern a layer of grease ice just beyond the edge. The water seemed to boil beneath us: the effect of current and wind cavitating. As the wind was gradually shifting to an offshore direction, we decided to call it a day and headed back to McMurdo.

Mt. Erebus	Hydrophone cable at the sea ice edge
Doug setting up at the sea ice edge	Samantha listens while Buck videotapes

Click to listen to a sample of the day's recording with leopard and Weddell seals.